1. Field of the Invention
The present invention relates generally to a turret punch press having a pair of upper and lower turrets rotatably mounted to automatically bring respective punch and dies into alignment for punching a variety of holes in sheet materials and, more particularly, to an apparatus for rotating the punch and die in the respective upper and lower turrets for punching holes in a variety of orientations.
2. Description of the Prior Art
It is known to provide rotatable punching tools in a turret punch press wherein the upper and lower punching tools are rotated synchronously for different orientations of the punch tools.
Hirata et al, U.S. Pat. No. 4,412,469 discloses a turret punch press having tool holders rotatably mounted in the turrets. Rotation of the tools is provided by servo motors mounted on brackets on the respective upper and lower portions of the punch press. An extensive series of transmitting elements for transmitting the rotational motion of the motor to the punch tool is shown, including a gear pair linking the drive shaft of the motor to a pulley, which operates through a belt to drive a pulley on a clutch and brake mechanism, which in turn operates through another pulley and a second belt to drive an idler pulley mounted on the turret, which through yet another pulley and a third belt drives a pulley encircling a holding member in which the punch tool is mounted. The clutch and brake mechanism provides a connectable linkage between the servo motors and the tools and includes a pneumatic or hydraulic motor to move a plurality of push rods in an upper portion of the clutch and brake mechanism which engage a respective plurality of bores in a lower portion of the clutch and brake mechanism. An annular friction plate restricts rotation of the lower portion when the push rods are disengaged. Magnets and sensing means are provided to detect the position of the idler pulley. It would be an improvement over the prior art to reduce the number of linkages between an indexable punch tool and a motor thereby increasing the accuracy and efficiency of the punch indexing mechanism. It would also be an improvement to provide a simpler, more reliable brake mechanism.